Ken Livingstone was today challenged to explain how he will fund nearly £3 billion of manifesto pledges.

The Labour candidate has made 24 promises during the election mayoral campaign including his seven per cent fares cut, establishing an energy co-operative and restoring the Education Maintenance Allowance.

Boris Johnson today said these pledges would cost a minimum of £2.7 billion. The Mayor claimed Mr Livingstone will have no choice but to dramatically increase taxes, unveil a new congestion charge or eventually ramp up the cost of fares if elected on May 3. Mr Livingstone today rejected the Mayor’s claims and accused him of “pure scaremongering”.

Mr Livingstone has repeatedly said he will freeze his share of council tax as well as the congestion charge if elected.

It comes as Mr Livingstone today announced he would reopen his foreign “embassies” to promote London abroad. In his manifesto, launched alongside Labour leader Ed Miliband in Greenwich, he pledged to rebuild an “effective overseas marketing operation” in India and China.

Mr Johnson shut the international operation — which cost £1.4 million a year — on taking over at City Hall in the face of opposition from businesses. In what is becoming an increasingly bitter contest, Mr Johnson today attacked Mr Livingstone for making “promises he will not be able to keep”.

Transport for London has said Mr Livingstone’s promise to cut fares by seven per cent would cost more than

£1 billion. Mr Livingstone claims the transport body has sufficient financial surpluses to cope. In addition to the fares cut, Mr Johnson claims his rival has made other transport promises which will cost TfL £482.5 million over four years.

These include his commitment to make one third of all Tube stations step-free at an estimated cost of £320 million.

Mr Johnson also said that promises such as restoring police numbers to 33,260 and creating a London-wide lettings agency would add a further £1.1 billion to the GLA’s budget.

Speaking to the Standard today in Enfield, Mr Johnson said: “Ken knows these aren’t deliverable but he’s in a position where he needs to say things that he knows are frankly impossible to realise.”

Mr Johnson said that to make up for the increases to the GLA budget, Mr Livingstone would have to increase his share of the council tax by £348 for a Band D property over four years.

The Mayor added: “What we’re identifying is that in order to fund some of these he would have to raise council tax or come up with a new congestion charge — maybe around Heathrow or across the whole of London. Or eventually he’d just have to put fares up anyway. There are only three real sources of income to finance this stuff.” Mr Livingstone said the Mayor had shown “no understanding” of the importance of setting up offices abroad. Their role included boosting jobs, securing inward investment and attracting tourism and foreign students.

Mr Livingstone claimed the offices — in Delhi, Mumbai, Beijing, Shanghai, Caracas and Brussels — were vital for investment in the capital. Explaining Mr Livingstone’s pledge to cut fares a spokesman said: “It will be financed out of the massive profits being built up at TfL — over £330 million is projected for 2011/12.

“Bringing back the EMA will be financed by pooling existing resources from universities, colleges and local authorities. Bulk buying electricity and heating is an innovative proposal that won’t cost the tax-payer a penny, but will save Londoners over £120 a year.”

The spokesman added: “Londoners are feeling the squeeze from a Tory government and Tory Mayor, from rising fares and the granny tax, to higher energy and water bills.”

Key issues: Where the candidates stand

BORIS JOHNSON

Economy Cut waste at City Hall. Freeze council tax. Create 200,000 new jobs over four years. Invest £221 million to transform high streets and support small businesses.

Transport Pave the way for driverless trains, in part to beat strikes. Lobby for powers over suburban rail. Cut Tube delays by a further 30 per cent. Extend Boris bikes. Bring in 600 new Routemasters.

Crime Maintain 1,000 extra police on streets. Move 2,000 officers from back-room jobs to front-line. Crack down on violent gangs. Make errant young people earn back free travel.

Economy Increase investment in London by re-establishing foreign offices. Make the London Living Wage a condition of procurement at the GLA. New apprenticeship scheme.

Transport Cut fares by 7 per cent by October of this year — or quit. Protect the Freedom Pass. Extend bike hire scheme to suburbs. Won’t reinstate Western C-charge zone or £25 gas guzzler charge. Scrap new Routemaster bus and invest in hybrids.

Environment/housing Bring in new non-profit lettings agency to cut out fees of private agents. Campaign for London Living Rent guaranteeing no more than third of income on rent. Boost affordable homes. Cut pollution. Cut energy bills.

BRIAN PADDICK

Economy Promote investment from abroad. Lead the “digital revolution” to ensure capital competes with the best in the world.

Transport Bring in One Hour Bus Ticket — hop on and off within one hour for cost of just one journey. Early Bird discounts for Tube and suburban rail before 7.30am. Travelcard for part-time workers and Outer Londoners. Review of all fare zones.

Housing/economy Build 360,000 more affordable homes over next 10 years. Crackdown on rogue landlords using Mayor’s “kitemark” for responsible renting. All buses, taxis and most vans running on electric by 2020. Two million trees planted before 2025. Long-term zero waste goal.